Objectives The aim of this study is to investigate the benefits on glycemic control following gastric bypass (GBP) for the type 2 diabetes (T2DM) patients with BMI <35 kg/m2.

Methods Thirty-four patients suffering from T2DM undergo laparoscopic gastric bypass surgery at Beijing Shijitan Hospital, Capital Medical University from June 2010 to April 2014 and were enrolled this study. The serum items including glucose, insulin and glycosylated haemoglobin (HbA1c) of all patients were measured before and after surgery and the results were analyzed.

Results 34 patients, the mean BMI was 29.50±2.88 kg/m2 before surgery, suffered from T2DM underwent GBP surgery successfully (a mean age of 44 years), 14 were male and 20 were female. The patients were followed up 6~12 months. No major complications. The mean BMI was 24.10±3.67 kg/m2 after surgery. The mean fasting blood glucose of all patients was10.06±3.30mmol/L (normal 3.90~6.10 mmol/L) before surgery and was significantly decreased (6.85 ±2.48mmol/L) (P<0.001) after surgery. The 0.5hr-, 1hr-, 2hr-, 3hr- postprandail blood glucose were also decreased respectively (P<0.001) in all patients after surgery. The fasting serum insulin was 15.50 ±10. 34µIU/ml before surgery and was 6.85 ±2.48µIU/ml after surgery. The mean 2hr-, 3hr-postprandail serum insulin of all patients was significantly decreased after surgery compared with those before surgery (P<0.001). Compared before and after surgery, there were no statistical difference in the levels of 0.5hr-, 1hr-postprandail serum insulin respectively in all patients (P>0.05). HbA1c of all patients dropped from an average of 8.8% (normal 4.8~6.0 %) preoperatively to 6.5% post operatively.

Conclusions This research shows that gastric bypass surgery in the T2DM patients with BMI <35 kg/m2 is a safe and effective procedure for glycemic control and the further study with long-term, large sample are needed.